Moisture meter or hygrometer



A Dec. 10, 1957 r.. `R. THOMAS" 2,815,662

' MOISTURE METER o3 HYGROMETEB Filed May 11, 195s Iilllillllllllllllll INVENTQR MOISTURE METER R HYGROMETER Thomas R. Thomas, New York, N. Y., assignor to Auto Research Corporation, Dover, D'el., a corporation of Delaware The present invention relates to indicators and it particularly relates to humidity indicators.

It is often desirable to be able, without too much accuracy, to determine whether the interior atmosphere in a closed vessel, mechanism or casing is of too high or too low humidity, and contains too much or too little moisture vapor, and it is among the objects of the present invention to provide a novel, simple, compact, inexpensive and reliable system indicating such humidity.

It is among the further objects of the present invention to provide simple, inexpensive, low cost humidity indicators which may be readily iitted into. existing mechanisms, casings, housings and the like, without changing the structure thereof, and which do not require elab orate controls or expensive mechanism likely to require servicing, or which would likely be aected by machine vibration, changes in temperature and the like.

Still further objects and advantages will appear in the more detailed description set forth below, it being understood, however, that this more detailed description is given by way of illustration and explanation only and not by way of limitation, since various changes therein may be made by those skilled in the art without departing from the scope and spirit of the present invention.

In accomplishing the above objects, it has been found most satisfactory according to one embodiment of the present invention to provide a thin, sheet metal casing of annular form in which there is positioned an absorbent,

sensitized disc which may be made of paper, different l will be a color change upon changes in humidity of the '45 portions of which have so been sensitized so that there type and character which it is desired to indicate. l Desirably, the annular casing, which may be presstted into an opening of the side of a housing, casing, container or reservoir, will be closed from the outside by means of a plastic or other transparent window, and on the inside it will have access to the gases, vapors or atmosphere within the chamber, housing or casing so that there may be a ready ow of gases into and out of the rear receptacle chamber of the measuring device.

In one preferred form, a paper which has been sensitized to lavender color is provided in back of the transparent window having a series of dierent colored marked areas thereon to match changes in the coloration upon in the circle or area which has changed color closest to the back ground which in the preferred form is lavender.

Instead of having an entire background of lavender or some other base color a central area or some other segregated area may be provided having the base color, as for example a central circle in the middle of the peripheral circles.

As an alternative procedure the background color may be caused to change to match the color of the selected discs which carry the numbers indicating the humidity.

In such case the background area or a segregated central area will change color while the varied colored enumerated areas will retain their same color and may be matched with the varying colors of the background or of the segregated area.

-Any variety of different colors may be employed where the base coloration will change with varying humidities and where the comparator non-changing or ixed colors will remain as standards of comparison and each give a predetermined reading.

With the foregoing and other objects in view the in-V vention consists of the novel construction, combination and arrangement of parts as hereinafter more specifically described, and illustrated in the accompanying drawings, wherein is shown an embodiment of the invention, but it is to be understood that changes, variations and modifications can be resorted to which fall within the scope of the claims hereunto appended.

In the drawings wherein like reference characters denote corresponding parts throughout the several views:

Fig. l is a front elevational view of one form of humidity indicator window unit according to the present invention.

Fig. 2 is a transverse vertical sectional View upon the line 2 2 of Fig. l.

Fig. 3 is a rear elevational view taken from the line 3-3 of Fig. 2.

Fig. 6 is an enlarged end of the sectional views of Figs. 2 and 5 showing the window unit construction and the assembly of the parts.

Referring toFigs. 2 and 3 there is shown a machine or casing structure A which may take the form of a mechanism in which a predetermined moisture content is to be maintained.

This mechanism is desired to receive the annular cup or casing B of the humidity indicator of the present invention which is provided with a transparent window C and with the absorbent sensitized indicating sheet D.

As indicated through the window C in Fig. l the main area 10 of the indicating sheet D may, for example, have a permanent pink or lavender color resulting from a sensitized dye which will vary with the moisture content or humidity of the interior of the casing A. Upon the paper disc D there is provided a series of marked circles with fixed or permanent colorations.

Illustratively the circle 11 will have a color which will indicate 20% humidity.

The circle 12 will indicate 30% humidity.

The circle 13 will indicate 40%l humidity, and the circle 14 will indicate 50% humidity.

As the humidity within the container or housing varies, the pink will change and become bluer so that it will match one f the circles 11, 12, 13 or 14, indicating 20, 5 indicated at 45 between the upper and lower half discs 15 30, 40 or 50% humidity by comparing or selecting the ld 1d61i to prevent possible moisture transfer between change color of the base which is closest to the xed an color of the circular areas 11, 12, 13 and 14, In another form of the invention the sheet D may be Instead 0f the circ1es 11, 1,2, 13 and 14 being fixed of apermanent non-sensitizedspink or lavender color and with the background coloration of die dise 10 cbang- 10 m front 0f therape D there @provided e Wmdevv havuglc ingffth.clortioiiofthecirclgill', 125213fand'14 may a series oi different color sensitized areas which will ehange1-wiih'iheebaekgronnn cnloraiion'g being fixed, In match the permanent coloration upon different internal such case the circle which most closely matchestli'e' humidties and enable a readyill'diaon' background coloration-willi give-I the' percentage or-"hir- When the moisture content within the housing or midity,` A c 1-v chamber changes thev sensitized areas will change color Instead offthewhoie backgroiiiidhavingfafsingie ooloreerrespendmgly andthe-area closest mcolor to thebasie ation whiebf eiih'eriss'vpeniianedi or iixedfa eeo'frai areax pink er lavenderA w111 mdleateth'e percentage 0f 1huriudlti/ between the circles 11, 12, 13 and 14 may havethe'fpe'r# 01' moisture registeredmanent'or-variable cloratiorr'or"ai-central circlefma'y'be Normally the coloration, say. a blue, pink orlavender providedibtwe'en 'the-lciicleslAl-g 12,1 13"andii14Ctof-pfovidelz 20 coloration, will' indictepre'seuce'of t'o'o' m'uch moisture, either tl'iedXedor ch'angingfcol'ortion. while other coloration-will indicate' too little moisture or f lathe-alternative *formf of-ca'r'dfo'rindi'cator,'asfshbwn that the air is too dry. inV Figi- 4, two different -sheets'' of pap'rlSan'd -16f=are- The comparison of colors will give a ready indication uticllizd,otreatthlejubperfprt-of tleechpofrecivi BCL" 25 at a glancdel as to whether the correct humidity is being an' `--t e o er at'it e" owerif'partio'-f-t'ecupo rec" Wei* .f 'maintai'r'ie v The upper sheet or half disc 15P mayfbese'nsitiaetl fo`i As many changes 'cculdfbefmadein the above india pinkcolor'sosthatit'willfchangefinhueas thihuni`itiity cato'rs; and manyfwidely'fdiierent embodiments of this increases `ordecreases.` Thelower p'ortion16"inay have a2v invention could, be'iriade without departing from the xedfcolorafor matchingthefcolorof theuppersectibh' scopefofthe'iclairs,itis`intended that all matter con- Whetn tht clolors1 "inatclllifthis will-givch-anl ilidicatiili! of- 30 talined' in 'theabovefdeslciiption'shall beinterpreted as one in erna umi 1y w ereas i one-isvpin eroi tierVV 1 ustrativel an ""noti l av ii'nitingfse'nse. than` the other a diierent indication willbegiveni`- 'Thief-paper' which: isused inthis application 'and which Theactualstructure of the-cup.l is show'n in-detai1` in is indicated at Disisatiated'fromifront vto back with the Fig. band in-'smaller-scalein Figs.'1 to5'. The"cphas 3f hur'r'i'idity-'st'ei's'iti've',"Y ldy'eilikefrrate'rial' which partakes of a cylindrical portion which fits in thel bored -orres' 0' a lavender or'pinkl'hueiatidwhich actslikejlitmus paper, cessed-opening26 in the-casing This Ac ylinciricalWall'- litir ii1s" paper''beinggsehsitivelto` acidlandthe pink or 'lIrs--agrlnove y27 vvlhifl-lmayzrelcelijveat-sealing conjpciu-rui,-y laviilililipp'eiof thefpie's'ent Vapi'il-ic'tioir being' sensitive is`w1 'assure a ere'wi e-'nopassage oiiair-or to'- u" i` it'yl l vapor into thesinteriorofthe-housingApast the humidity.' Theexact forrriultbiiof'the'se" papers isl not available indliqclator unil of 1-to5.- h Id 28 t h h 4"ar1d they' ae madel by 'secr-fet processes 'by' various firms e vcup wi aveA a's ou er agains w 1c 1S w o specia i'zef iniitsmauu vactui'e. Pressed th@ gasket 29- EXI1dI1g`hrO11gh the Wild-'30 Materialsl such asi nitrazine (2V-4edinitro-ben'zene-azoattheend ofthe shoulder will be the side openings' '31: 1nph'th13`6`disotim disulfnate), lacmoid, rosolic These Openings permit free flew 0f vapors and gases'fromA aoidvs'o'dium ali'zaiiiifsiiifonaie brom-phenol blue bromthe interior of thelhousingi A-into the rear exposure 'chan'f- 45" thyffoli' blue; methyl red and' neutral red" may. be ember 32 of the indicator unit. The cup unitB then-hasea'f p1oy',z ldubeed ilgvardextensienf, havingv the sidewalls 34 and Having 'newip 'ariio'uiariy described and ascertained theY e ase K natureyfo'f'?tlie'invnn; and' iii'whatmanner'the'same fl'fhe openings.ilextendy asubstantialfdistance from the 50 I is :f5.zb-pel-zfndg Wha-fais :ciimed 'isz perlphery 0f the base 35 t0 the i101ntsv36 adjacent-libe 1.1humidity-indicator win`dow1'iioit` insert, designed Center 1111@ 0f the C9113- Y robes-insertedidiofaosopening-ioihe wan of a housing T he' edges or peripher) 0f. ille WIFQW C1 d QSelY f t havi'ug an"atnosph"ere= thehu'n'iidity 'f of which is to beA agamst the vva11 25 e11den the1cryssldefaeefh? WKIHQOYQIA? measured; ii'ietaii in wiiioii is= iosb'ei maintained at a de: covered by the indicator paper disc Dor bythe half discsv sir-dg-humidty.; saidfindicafrcomprising apresslin cylin- The window C is pressed against'the p'aperdisc""`oi" thefhalf discs l15 and `169which inturn are' pressed against the gasket2'9 by'theiiiiiirnediips-or edges'5s'ai'th'efront'l or outside edge of the'cup B.'

The applicant thus has provided a simpleginexpeisive', readily assembled, reliable` humidity indicator consisting of a window unit insert which will giveiaready.-guidev to the interior humidity.

The embodiment of Figs; 1 and2v areparticularly suit' able where it is necessary to keep a close checkuponllow humidities between 20 andSO".

The openingso may be in-any position andinore than two maybe provided" so as topermit fr'ee' flowofthe internal atmospherethrough tliecha'mberi back"of"'th'e"' sheets 15 and 16.

Thief-arrangement of Figs. 3' and 4 is particulalyuse'i' ful in keeping a writtencheck'as"to"whetherthe'hiidity" is correct--or off withoutr` giving' percentages asis triieiu connection with Figs. 1 and 2. Foi-"exampliajmatchl" ing of the colorsloffth'ehlves 1'5":aiid ld'wouldlindicat 4 that the correct humidity is being maintained, and an unmatch would indicate that a correct humidity is not being maintained.

In the arrangement shown in Fig. 4 the separation as drical wall, bttomfsteppedcupi-said! wall havinga'pe ripheral groove"receiving'sealing4 material and' said cup havin'gja window, a'nA in'dicator'discofthe type' consisting of va sheet of impregnated' material whichwill change in colorwith cliaiigof' humidity visiblydisplayed in'b'a'ck of said` window and V av .rear` cha'mb'er" in' communication with thevinte'rior" of thei housing" and casing, said disc' plasticwindow beingadapied-'to be located' insides'aid cylindrical member; said casi'ri'g''corprising af'ba'ckr charnbeiffvorming a cupofreduceddiameter,constituting'afexl ing a rear wall and a cylindrical peripheral wall, said rear wall and peripheral wall having at the juncture thereof diametrically opposite large ow openings extending partly into said rear wall and partly into said peripheral wall, said cup being formed with a rim portion constitut- 5 ing a shoulder against which said gasket and Window are mounted, and said rim portion having a forward extension which is turned inwardly to bite against the periphery of the plastic window, and a humidity indicator sheet being positioned between said window and gasket. 10

References Cited in the le of this patent UNITED STATES PATENTS Howard May 22, 1900 Looram Jan. 9, 1912 Crocker Sept. 4, 1923 Hickman Nov. 7, 1933 Snelling July 22, 1941 Kocher Oct. 19, 1943 Clibbon Aug. 3, 1948 Vacanti May 19, 1953 FOREIGN PATENTS Great Britain Jan. 26, 1928 

